please answer 7 and 8

7. The sun generates an average of 3.74000\"5 W (watt = 1/5) power. Assuming the wavelength of the sun's radiation to be 500 nm, determine how many photons the sun emits every second. (10) 8. Consider an electron of mass m and charge e moving in a circular orbit of radius \"a\" about a xed charge +e at the origin. What should be the radius of the orbit if the velocity of the orbiting electron is 0.069 Jth'5 m/s, e=l .60x10"9 c, 80 = 8.85 x10"2 c2 /N.n12, m = 9.109 x1023 g, so that rotating electron remains in the orbit. Hint: Centrilgal force should be balanced by the attractive force